1. Field of the Invention
The present invention relates to a composition for forming solder bumps on a pad of a member (e.g., a wiring board, an electronic part, or the like) (hereinafter, the composition is referred to as a “solder bump formation resin composition”), to a solder bump formation method employing the composition, and to a member having solder bumps.
2. Background Art
Generally, various electronic parts (e.g., LSIs and WLPs (wafer level packages)) employed in semiconductor devices and the like are mounted on printed wiring boards though soldering. In one method for mounting such parts on a printed wiring board in a flip-chip manner, a solder paste is printed on pads of a substrate on which devices are to be mounted, and the substrate is subjected to reflowing and washing, to thereby form solder bumps on the pads. The solder bumps formed on the substrate are brought into contact with the solder bumps formed on the device, and the substrate and device are heated to join to each other, to thereby complete solder bonding of the device.
Meanwhile, in a recent years' trend for increasing packaging density of such devices, a micro-wiring pattern is demanded, and electrode pads have become smaller. Thus, solder bumps formed through a conventional dip soldering technique or solder paste printing technique cause problems such as variation in solder amount resulting in mounting failures, and formation of a solder bridge between adjacent electrodes.
Instead of such a conventional dip soldering technique or solder paste printing technique, Patent Document 1 proposes a solder bonding method employing a dry film. This method employs a solder paste containing rosin and an activating agent.
However, when the above method is employed, the dry film is heated to high temperature during formation of solder bumps through reflowing or baking. As a result, residues of the dry film remain in the vicinity of the solder bumps, which is problematic.
Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2000-208911